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Multidrug resistance (MDR) remains a burden in cancer chemotherapy. Several members of ATP-binding cassette (ABC transporters) are responsible for the efflux of anticancer drugs outside cells decreasing the drug’s effective intracellular concentration. Therefore, extensive efforts have been conducted by researcher to circumvent the activity of these transporters to enhance the success of chemotherapy. In the present study, we questioned the role played by two microRNAs, namely miR-98 and miR-214 in controlling their bioinformatics’ predicted ABC efflux transporter targets ABCC5 and ABCC10, in addition to ABCB1 and ABCC1 in doxorubicin-resistant HCC cells (HepG2/Dox). miRNA mimics and inhibitors transfection were utilized to explore the role of both candidate molecules in MDR in HepG2/Dox cells. QRT-PCR and western blotting were used for quantitative gene and protein analyses. The study revealed that miR-214 mimics significantly upregulated ABCC1 and ABCC5. While, miR-98 and miR-214 inhibitors significantly down regulated ABCC5 and ABCC10, respectively. These results introduced a possible negative role played by both miR-98 and miR-214 on drug sensitization. Moreover, these findings clarified that the predicted targets for miR-98 and miR-214 were not confirmed experimentally. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is a hypervascular primary liver cancer characterized by rapid progression , besides, resistance to traditional chemotherapeutic agents. It has been shown that microRNAs play critical roles in regulation of tumor cell sensitivity to drugs. The present study investigated whether restoration of mir-122 in HCC cells could alter the cell cycle distribution and the expression of multidrug resistance (MDR)-related genes (ABCB1, ABCC1, ABCG2 and ABCF2). After overexpression of mir-122 in HepG2 cells treated or untreated with doxorubicin doses, total RNAs and protein extracts were isolated for application of QRT-PCR and western blotting techniques. Moreover, cell cycle distribution was monitored by flowcytometry. Our results revealed that, the over expression of mir-122 in HepG2 cells treated or untreated with doxorubicin could modulate the sensitivity of cells to chemotherapeutic drug through downregulation of MDR-related genes, ABCB1and ABCF2. The antiproliferative effect of mir-122 is associated with the accumulation of cells in G0/G1 phase. Moreover, treatment with mir-122 and doxorubicin resulted in high percentage of HCC cells in G0/G1 phase. Taken together, our findings revealed that, overexpression of mir-122 inhibited HCC cell growth by inducing cell cycle arrest and this arrest is associated with down-regulation of MDR-related genes. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is a hypervascular primary liver cancer characterized by rapid progression, besides, resistance to traditional chemotherapeutic agents. It has been shown that microRNAs play critical roles in regulation of tumor cell sensitivity to drugs through modulating the expression of genes involved in drug transport. The present study investigated whether restoration of miR-122 in HCC cells could alter the cell cycle distribution and the expression of multidrug resistance (MDR)-related genes (ABCB1, ABCC1, ABCG2 and ABCF2). After overexpression of miR-122 in HepG2 cells treated or untreated with doxorubicin doses, total RNAs and protein extracts were isolated for application of QRT-PCR and western blotting techniques. Moreover, cell cycle distribution was monitored by flow cytometry. Our results revealed that, the over expression of miR-122 in HepG2 cells treated or untreated with doxorubicin could modulate the sensitivity of cells to chemotherapeutic drug through downregulation of MDR-related genes, ABCB1 and ABCF2. Interpretation of cell cycle distribution revealed that, the anti-proliferative effect of miR-122 is associated with the accumulation of cells in G 0 /G1 phase. Moreover, treatment with miR-122 and doxorubicin resulted in high percentage of HCC cells in G 0 /G1 phase. Taken together, our findings revealed that, overexpression of miR-122 inhibited HCC cell growth by inducing cell cycle arrest and this arrest is associated with down-regulation of MDR-related genes., Competing Interests: Compliance with Ethical StandardsThe authors declare that they have no conflict of interest.This article does not contain any studies with human participants or animals performed by any of the authors.